drivers/mtd/ubi/upd.c

   1 /*
   2  * Copyright (c) International Business Machines Corp., 2006
   3  * Copyright (c) Nokia Corporation, 2006
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
  13  * the GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  18  *
  19  * Author: Artem Bityutskiy (Битюцкий Артём)
  20  *
  21  * Jan 2007: Alexander Schmidt, hacked per-volume update.
  22  */
  23
  24 /*
  25  * This file contains implementation of the volume update functionality.
  26  *
  27  * The update operation is based on the per-volume update marker which is
  28  * stored in the volume table. The update marker is set before the update
  29  * starts, and removed after the update has been finished. So if the update was
  30  * interrupted by an unclean re-boot or due to some other reasons, the update
  31  * marker stays on the flash media and UBI finds it when it attaches the MTD
  32  * device next time. If the update marker is set for a volume, the volume is
  33  * treated as damaged and most I/O operations are prohibited. Only a new update
  34  * operation is allowed.
  35  *
  36  * Note, in general it is possible to implement the update operation as a
  37  * transaction with a roll-back capability.
  38  */
  39
  40 #include <linux/err.h>
  41 #include <asm/uaccess.h>
  42 #include <asm/div64.h>
  43 #include "ubi.h"
  44
  45 /**
  46  * set_update_marker - set update marker.
  47  * @ubi: UBI device description object
  48  * @vol_id: volume ID
  49  *
  50  * This function sets the update marker flag for volume @vol_id. Returns zero
  51  * in case of success and a negative error code in case of failure.
  52  */
  53 static int set_update_marker(struct ubi_device *ubi, int vol_id)
  54 {
  55         int err;
  56         struct ubi_vtbl_record vtbl_rec;
  57         struct ubi_volume *vol = ubi->volumes[vol_id];
  58
  59         dbg_msg("set update marker for volume %d", vol_id);
  60
  61         if (vol->upd_marker) {
  62                 ubi_assert(ubi->vtbl[vol_id].upd_marker);
  63                 dbg_msg("already set");
  64                 return 0;
  65         }
  66
  67         memcpy(&vtbl_rec, &ubi->vtbl[vol_id], sizeof(struct ubi_vtbl_record));
  68         vtbl_rec.upd_marker = 1;
  69
  70         err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
  71         vol->upd_marker = 1;
  72         return err;
  73 }
  74
  75 /**
  76  * clear_update_marker - clear update marker.
  77  * @ubi: UBI device description object
  78  * @vol_id: volume ID
  79  * @bytes: new data size in bytes
  80  *
  81  * This function clears the update marker for volume @vol_id, sets new volume
  82  * data size and clears the "corrupted" flag (static volumes only). Returns
  83  * zero in case of success and a negative error code in case of failure.
  84  */
  85 static int clear_update_marker(struct ubi_device *ubi, int vol_id, long long bytes)
  86 {
  87         int err;
  88         uint64_t tmp;
  89         struct ubi_vtbl_record vtbl_rec;
  90         struct ubi_volume *vol = ubi->volumes[vol_id];
  91
  92         dbg_msg("clear update marker for volume %d", vol_id);
  93
  94         memcpy(&vtbl_rec, &ubi->vtbl[vol_id], sizeof(struct ubi_vtbl_record));
  95         ubi_assert(vol->upd_marker && vtbl_rec.upd_marker);
  96         vtbl_rec.upd_marker = 0;
  97
  98         if (vol->vol_type == UBI_STATIC_VOLUME) {
  99                 vol->corrupted = 0;
 100                 vol->used_bytes = tmp = bytes;
 101                 vol->last_eb_bytes = do_div(tmp, vol->usable_leb_size);
 102                 vol->used_ebs = tmp;
 103                 if (vol->last_eb_bytes)
 104                         vol->used_ebs += 1;
 105                 else
 106                         vol->last_eb_bytes = vol->usable_leb_size;
 107         }
 108
 109         err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
 110         vol->upd_marker = 0;
 111         return err;
 112 }
 113
 114 /**
 115  * ubi_start_update - start volume update.
 116  * @ubi: UBI device description object
 117  * @vol_id: volume ID
 118  * @bytes: update bytes
 119  *
 120  * This function starts volume update operation. If @bytes is zero, the volume
 121  * is just wiped out. Returns zero in case of success and a negative error code
 122  * in case of failure.
 123  */
 124 int ubi_start_update(struct ubi_device *ubi, int vol_id, long long bytes)
 125 {
 126         int i, err;
 127         uint64_t tmp;
 128         struct ubi_volume *vol = ubi->volumes[vol_id];
 129
 130         dbg_msg("start update of volume %d, %llu bytes", vol_id, bytes);
 131         vol->updating = 1;
 132
 133         err = set_update_marker(ubi, vol_id);
 134         if (err)
 135                 return err;
 136
 137         /* Before updating - wipe out the volume */
 138         for (i = 0; i < vol->reserved_pebs; i++) {
 139                 err = ubi_eba_unmap_leb(ubi, vol_id, i);
 140                 if (err)
 141                         return err;
 142         }
 143
 144         if (bytes == 0) {
 145                 err = clear_update_marker(ubi, vol_id, 0);
 146                 if (err)
 147                         return err;
 148                 err = ubi_wl_flush(ubi);
 149                 if (!err)
 150                         vol->updating = 0;
 151         }
 152
 153         vol->upd_buf = kmalloc(ubi->leb_size, GFP_KERNEL);
 154         if (!vol->upd_buf)
 155                 return -ENOMEM;
 156
 157         tmp = bytes;
 158         vol->upd_ebs = !!do_div(tmp, vol->usable_leb_size);
 159         vol->upd_ebs += tmp;
 160         vol->upd_bytes = bytes;
 161         vol->upd_received = 0;
 162         return 0;
 163 }
 164
 165 /**
 166  * write_leb - write update data.
 167  * @ubi: UBI device description object
 168  * @vol_id: volume ID
 169  * @lnum: logical eraseblock number
 170  * @buf: data to write
 171  * @len: data size
 172  * @used_ebs: how many logical eraseblocks will this volume contain (static
 173  * volumes only)
 174  *
 175  * This function writes update data to corresponding logical eraseblock. In
 176  * case of dynamic volume, this function checks if the data contains 0xFF bytes
 177  * at the end. If yes, the 0xFF bytes are cut and not written. So if the whole
 178  * buffer contains only 0xFF bytes, the LEB is left unmapped.
 179  *
 180  * The reason why we skip the trailing 0xFF bytes in case of dynamic volume is
 181  * that we want to make sure that more data may be appended to the logical
 182  * eraseblock in future. Indeed, writing 0xFF bytes may have side effects and
 183  * this PEB won't be writable anymore. So if one writes the file-system image
 184  * to the UBI volume where 0xFFs mean free space - UBI makes sure this free
 185  * space is writable after the update.
 186  *
 187  * We do not do this for static volumes because they are read-only. But this
 188  * also cannot be done because we have to store per-LEB CRC and the correct
 189  * data length.
 190  *
 191  * This function returns zero in case of success and a negative error code in
 192  * case of failure.
 193  */
 194 static int write_leb(struct ubi_device *ubi, int vol_id, int lnum, void *buf,
 195                      int len, int used_ebs)
 196 {
 197         int err, l;
 198         struct ubi_volume *vol = ubi->volumes[vol_id];
 199
 200         if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
 201                 l = ALIGN(len, ubi->min_io_size);
 202                 memset(buf + len, 0xFF, l - len);
 203
 204                 l = ubi_calc_data_len(ubi, buf, l);
 205                 if (l == 0) {
 206                         dbg_msg("all %d bytes contain 0xFF - skip", len);
 207                         return 0;
 208                 }
 209                 if (len != l)
 210                         dbg_msg("skip last %d bytes (0xFF)", len - l);
 211
 212                 err = ubi_eba_write_leb(ubi, vol_id, lnum, buf, 0, l,
 213                                         UBI_UNKNOWN);
 214         } else {
 215                 /*
 216                  * When writing static volume, and this is the last logical
 217                  * eraseblock, the length (@len) does not have to be aligned to
 218                  * the minimal flash I/O unit. The 'ubi_eba_write_leb_st()'
 219                  * function accepts exact (unaligned) length and stores it in
 220                  * the VID header. And it takes care of proper alignment by
 221                  * padding the buffer. Here we just make sure the padding will
 222                  * contain zeros, not random trash.
 223                  */
 224                 memset(buf + len, 0, vol->usable_leb_size - len);
 225                 err = ubi_eba_write_leb_st(ubi, vol_id, lnum, buf, len,
 226                                            UBI_UNKNOWN, used_ebs);
 227         }
 228
 229         return err;
 230 }
 231
 232 /**
 233  * ubi_more_update_data - write more update data.
 234  * @vol: volume description object
 235  * @buf: write data (user-space memory buffer)
 236  * @count: how much bytes to write
 237  *
 238  * This function writes more data to the volume which is being updated. It may
 239  * be called arbitrary number of times until all of the update data arrive.
 240  * This function returns %0 in case of success, number of bytes written during
 241  * the last call if the whole volume update was successfully finished, and a
 242  * negative error code in case of failure.
 243  */
 244 int ubi_more_update_data(struct ubi_device *ubi, int vol_id,
 245                          const void __user *buf, int count)
 246 {
 247         uint64_t tmp;
 248         struct ubi_volume *vol = ubi->volumes[vol_id];
 249         int lnum, offs, err = 0, len, to_write = count;
 250
 251         dbg_msg("write %d of %lld bytes, %lld already passed",
 252                 count, vol->upd_bytes, vol->upd_received);
 253
 254         if (ubi->ro_mode)
 255                 return -EROFS;
 256
 257         tmp = vol->upd_received;
 258         offs = do_div(tmp, vol->usable_leb_size);
 259         lnum = tmp;
 260
 261         if (vol->upd_received + count > vol->upd_bytes)
 262                 to_write = count = vol->upd_bytes - vol->upd_received;
 263
 264         /*
 265          * When updating volumes, we accumulate whole logical eraseblock of
 266          * data and write it at once.
 267          */
 268         if (offs != 0) {
 269                 /*
 270                  * This is a write to the middle of the logical eraseblock. We
 271                  * copy the data to our update buffer and wait for more data or
 272                  * flush it if the whole eraseblock is written or the update
 273                  * is finished.
 274                  */
 275
 276                 len = vol->usable_leb_size - offs;
 277                 if (len > count)
 278                         len = count;
 279
 280                 err = copy_from_user(vol->upd_buf + offs, buf, len);
 281                 if (err)
 282                         return -EFAULT;
 283
 284                 if (offs + len == vol->usable_leb_size ||
 285                     vol->upd_received + len == vol->upd_bytes) {
 286                         int flush_len = offs + len;
 287
 288                         /*
 289                          * OK, we gathered either the whole eraseblock or this
 290                          * is the last chunk, it's time to flush the buffer.
 291                          */
 292                         ubi_assert(flush_len <= vol->usable_leb_size);
 293                         err = write_leb(ubi, vol_id, lnum, vol->upd_buf,
 294                                         flush_len, vol->upd_ebs);
 295                         if (err)
 296                                 return err;
 297                 }
 298
 299                 vol->upd_received += len;
 300                 count -= len;
 301                 buf += len;
 302                 lnum += 1;
 303         }
 304
 305         /*
 306          * If we've got more to write, let's continue. At this point we know we
 307          * are starting from the beginning of an eraseblock.
 308          */
 309         while (count) {
 310                 if (count > vol->usable_leb_size)
 311                         len = vol->usable_leb_size;
 312                 else
 313                         len = count;
 314
 315                 err = copy_from_user(vol->upd_buf, buf, len);
 316                 if (err)
 317                         return -EFAULT;
 318
 319                 if (len == vol->usable_leb_size ||
 320                     vol->upd_received + len == vol->upd_bytes) {
 321                         err = write_leb(ubi, vol_id, lnum, vol->upd_buf, len,
 322                                         vol->upd_ebs);
 323                         if (err)
 324                                 break;
 325                 }
 326
 327                 vol->upd_received += len;
 328                 count -= len;
 329                 lnum += 1;
 330                 buf += len;
 331         }
 332
 333         ubi_assert(vol->upd_received <= vol->upd_bytes);
 334         if (vol->upd_received == vol->upd_bytes) {
 335                 /* The update is finished, clear the update marker */
 336                 err = clear_update_marker(ubi, vol_id, vol->upd_bytes);
 337                 if (err)
 338                         return err;
 339                 err = ubi_wl_flush(ubi);
 340                 if (err == 0) {
 341                         err = to_write;
 342                         kfree(vol->upd_buf);
 343                         vol->updating = 0;
 344                 }
 345         }
 346
 347         return err;
 348 }